P2234: O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 1
What to do
Expect hesitation and reduced power on a lean-running bank, and avoid sustained heavy load until it is fixed. Mention any recent exhaust or manifold work on that side of the engine, and any aftermarket sensor fitted — a wire melted against the exhaust or a splice made wrongly gives this code on a healthy sensor, and both are local to one bank.
What this code means
The short described at P2231, on the upstream sensor of the second cylinder bank. The mechanism, the fuelling consequence and the diagnostic tell are all unchanged: the signal is driven by heater voltage rather than by exhaust oxygen, the module removes fuel in response, and the engine runs lean on that bank.
The bank-specific point is one the corpus makes throughout this range and it is genuinely useful here: this fault, unlike most oxygen sensor faults, has a physical cause that can travel. A harness routed against the exhaust on one side, a connector damaged during work on one manifold, or one splice made incorrectly are all local to a bank — so a single-bank code points at a specific piece of loom on a specific side, which is a much smaller search than the sensor family usually allows.
Both banks shorting at once is rare enough to be worth questioning rather than accepting. Two sensors developing the same internal fault simultaneously is unlikely; a common harness route where both looms pass a hot component is the better hypothesis.
Likely causes
Start here
- Internal short in the oxygen sensor · moderate
- Melted wiring against the exhaust · moderate
- Incorrectly wired universal oxygen sensor · moderate
- Damaged wiring harness · moderate
Less common
Symptoms
Components involved
Information, not instruction
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Community experience
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